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1 <html>
2 <head>
3 <title>pcretest specification</title>
4 </head>
5 <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6 <h1>pcretest man page</h1>
7 <p>
8 Return to the <a href="index.html">PCRE index page</a>.
9 </p>
10 <p>
11 This page is part of the PCRE HTML documentation. It was generated automatically
12 from the original man page. If there is any nonsense in it, please consult the
13 man page, in case the conversion went wrong.
14 <br>
15 <ul>
16 <li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
17 <li><a name="TOC2" href="#SEC2">OPTIONS</a>
18 <li><a name="TOC3" href="#SEC3">DESCRIPTION</a>
19 <li><a name="TOC4" href="#SEC4">PATTERN MODIFIERS</a>
20 <li><a name="TOC5" href="#SEC5">DATA LINES</a>
21 <li><a name="TOC6" href="#SEC6">THE ALTERNATIVE MATCHING FUNCTION</a>
22 <li><a name="TOC7" href="#SEC7">DEFAULT OUTPUT FROM PCRETEST</a>
23 <li><a name="TOC8" href="#SEC8">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a>
24 <li><a name="TOC9" href="#SEC9">RESTARTING AFTER A PARTIAL MATCH</a>
25 <li><a name="TOC10" href="#SEC10">CALLOUTS</a>
26 <li><a name="TOC11" href="#SEC11">NON-PRINTING CHARACTERS</a>
27 <li><a name="TOC12" href="#SEC12">SAVING AND RELOADING COMPILED PATTERNS</a>
28 <li><a name="TOC13" href="#SEC13">SEE ALSO</a>
29 <li><a name="TOC14" href="#SEC14">AUTHOR</a>
30 <li><a name="TOC15" href="#SEC15">REVISION</a>
31 </ul>
32 <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
33 <P>
34 <b>pcretest [options] [source] [destination]</b>
35 <br>
36 <br>
37 <b>pcretest</b> was written as a test program for the PCRE regular expression
38 library itself, but it can also be used for experimenting with regular
39 expressions. This document describes the features of the test program; for
40 details of the regular expressions themselves, see the
41 <a href="pcrepattern.html"><b>pcrepattern</b></a>
42 documentation. For details of the PCRE library function calls and their
43 options, see the
44 <a href="pcreapi.html"><b>pcreapi</b></a>
45 documentation.
46 </P>
47 <br><a name="SEC2" href="#TOC1">OPTIONS</a><br>
48 <P>
49 <b>-b</b>
50 Behave as if each regex has the <b>/B</b> (show bytecode) modifier; the internal
51 form is output after compilation.
52 </P>
53 <P>
54 <b>-C</b>
55 Output the version number of the PCRE library, and all available information
56 about the optional features that are included, and then exit.
57 </P>
58 <P>
59 <b>-d</b>
60 Behave as if each regex has the <b>/D</b> (debug) modifier; the internal
61 form and information about the compiled pattern is output after compilation;
62 <b>-d</b> is equivalent to <b>-b -i</b>.
63 </P>
64 <P>
65 <b>-dfa</b>
66 Behave as if each data line contains the \D escape sequence; this causes the
67 alternative matching function, <b>pcre_dfa_exec()</b>, to be used instead of the
68 standard <b>pcre_exec()</b> function (more detail is given below).
69 </P>
70 <P>
71 <b>-help</b>
72 Output a brief summary these options and then exit.
73 </P>
74 <P>
75 <b>-i</b>
76 Behave as if each regex has the <b>/I</b> modifier; information about the
77 compiled pattern is given after compilation.
78 </P>
79 <P>
80 <b>-m</b>
81 Output the size of each compiled pattern after it has been compiled. This is
82 equivalent to adding <b>/M</b> to each regular expression. For compatibility
83 with earlier versions of pcretest, <b>-s</b> is a synonym for <b>-m</b>.
84 </P>
85 <P>
86 <b>-o</b> <i>osize</i>
87 Set the number of elements in the output vector that is used when calling
88 <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> to be <i>osize</i>. The default value
89 is 45, which is enough for 14 capturing subexpressions for <b>pcre_exec()</b> or
90 22 different matches for <b>pcre_dfa_exec()</b>. The vector size can be
91 changed for individual matching calls by including \O in the data line (see
92 below).
93 </P>
94 <P>
95 <b>-p</b>
96 Behave as if each regex has the <b>/P</b> modifier; the POSIX wrapper API is
97 used to call PCRE. None of the other options has any effect when <b>-p</b> is
98 set.
99 </P>
100 <P>
101 <b>-q</b>
102 Do not output the version number of <b>pcretest</b> at the start of execution.
103 </P>
104 <P>
105 <b>-S</b> <i>size</i>
106 On Unix-like systems, set the size of the runtime stack to <i>size</i>
107 megabytes.
108 </P>
109 <P>
110 <b>-t</b>
111 Run each compile, study, and match many times with a timer, and output
112 resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with
113 <b>-t</b>, because you will then get the size output a zillion times, and the
114 timing will be distorted. You can control the number of iterations that are
115 used for timing by following <b>-t</b> with a number (as a separate item on the
116 command line). For example, "-t 1000" would iterate 1000 times. The default is
117 to iterate 500000 times.
118 </P>
119 <P>
120 <b>-tm</b>
121 This is like <b>-t</b> except that it times only the matching phase, not the
122 compile or study phases.
123 </P>
124 <br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br>
125 <P>
126 If <b>pcretest</b> is given two filename arguments, it reads from the first and
127 writes to the second. If it is given only one filename argument, it reads from
128 that file and writes to stdout. Otherwise, it reads from stdin and writes to
129 stdout, and prompts for each line of input, using "re&#62;" to prompt for regular
130 expressions, and "data&#62;" to prompt for data lines.
131 </P>
132 <P>
133 The program handles any number of sets of input on a single input file. Each
134 set starts with a regular expression, and continues with any number of data
135 lines to be matched against the pattern.
136 </P>
137 <P>
138 Each data line is matched separately and independently. If you want to do
139 multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
140 etc., depending on the newline setting) in a single line of input to encode the
141 newline sequences. There is no limit on the length of data lines; the input
142 buffer is automatically extended if it is too small.
143 </P>
144 <P>
145 An empty line signals the end of the data lines, at which point a new regular
146 expression is read. The regular expressions are given enclosed in any
147 non-alphanumeric delimiters other than backslash, for example:
148 <pre>
149 /(a|bc)x+yz/
150 </pre>
151 White space before the initial delimiter is ignored. A regular expression may
152 be continued over several input lines, in which case the newline characters are
153 included within it. It is possible to include the delimiter within the pattern
154 by escaping it, for example
155 <pre>
156 /abc\/def/
157 </pre>
158 If you do so, the escape and the delimiter form part of the pattern, but since
159 delimiters are always non-alphanumeric, this does not affect its interpretation.
160 If the terminating delimiter is immediately followed by a backslash, for
161 example,
162 <pre>
163 /abc/\
164 </pre>
165 then a backslash is added to the end of the pattern. This is done to provide a
166 way of testing the error condition that arises if a pattern finishes with a
167 backslash, because
168 <pre>
169 /abc\/
170 </pre>
171 is interpreted as the first line of a pattern that starts with "abc/", causing
172 pcretest to read the next line as a continuation of the regular expression.
173 </P>
174 <br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
175 <P>
176 A pattern may be followed by any number of modifiers, which are mostly single
177 characters. Following Perl usage, these are referred to below as, for example,
178 "the <b>/i</b> modifier", even though the delimiter of the pattern need not
179 always be a slash, and no slash is used when writing modifiers. Whitespace may
180 appear between the final pattern delimiter and the first modifier, and between
181 the modifiers themselves.
182 </P>
183 <P>
184 The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
185 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
186 <b>pcre_compile()</b> is called. These four modifier letters have the same
187 effect as they do in Perl. For example:
188 <pre>
189 /caseless/i
190 </pre>
191 The following table shows additional modifiers for setting PCRE options that do
192 not correspond to anything in Perl:
193 <pre>
194 <b>/A</b> PCRE_ANCHORED
195 <b>/C</b> PCRE_AUTO_CALLOUT
196 <b>/E</b> PCRE_DOLLAR_ENDONLY
197 <b>/f</b> PCRE_FIRSTLINE
198 <b>/J</b> PCRE_DUPNAMES
199 <b>/N</b> PCRE_NO_AUTO_CAPTURE
200 <b>/U</b> PCRE_UNGREEDY
201 <b>/X</b> PCRE_EXTRA
202 <b>/&#60;cr&#62;</b> PCRE_NEWLINE_CR
203 <b>/&#60;lf&#62;</b> PCRE_NEWLINE_LF
204 <b>/&#60;crlf&#62;</b> PCRE_NEWLINE_CRLF
205 <b>/&#60;anycrlf&#62;</b> PCRE_NEWLINE_ANYCRLF
206 <b>/&#60;any&#62;</b> PCRE_NEWLINE_ANY
207 </pre>
208 Those specifying line ending sequencess are literal strings as shown. This
209 example sets multiline matching with CRLF as the line ending sequence:
210 <pre>
211 /^abc/m&#60;crlf&#62;
212 </pre>
213 Details of the meanings of these PCRE options are given in the
214 <a href="pcreapi.html"><b>pcreapi</b></a>
215 documentation.
216 </P>
217 <br><b>
218 Finding all matches in a string
219 </b><br>
220 <P>
221 Searching for all possible matches within each subject string can be requested
222 by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
223 again to search the remainder of the subject string. The difference between
224 <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
225 <b>pcre_exec()</b> to start searching at a new point within the entire string
226 (which is in effect what Perl does), whereas the latter passes over a shortened
227 substring. This makes a difference to the matching process if the pattern
228 begins with a lookbehind assertion (including \b or \B).
229 </P>
230 <P>
231 If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
232 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
233 flags set in order to search for another, non-empty, match at the same point.
234 If this second match fails, the start offset is advanced by one, and the normal
235 match is retried. This imitates the way Perl handles such cases when using the
236 <b>/g</b> modifier or the <b>split()</b> function.
237 </P>
238 <br><b>
239 Other modifiers
240 </b><br>
241 <P>
242 There are yet more modifiers for controlling the way <b>pcretest</b>
243 operates.
244 </P>
245 <P>
246 The <b>/+</b> modifier requests that as well as outputting the substring that
247 matched the entire pattern, pcretest should in addition output the remainder of
248 the subject string. This is useful for tests where the subject contains
249 multiple copies of the same substring.
250 </P>
251 <P>
252 The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
253 output a representation of the compiled byte code after compilation. Normally
254 this information contains length and offset values; however, if <b>/Z</b> is
255 also present, this data is replaced by spaces. This is a special feature for
256 use in the automatic test scripts; it ensures that the same output is generated
257 for different internal link sizes.
258 </P>
259 <P>
260 The <b>/L</b> modifier must be followed directly by the name of a locale, for
261 example,
262 <pre>
263 /pattern/Lfr_FR
264 </pre>
265 For this reason, it must be the last modifier. The given locale is set,
266 <b>pcre_maketables()</b> is called to build a set of character tables for the
267 locale, and this is then passed to <b>pcre_compile()</b> when compiling the
268 regular expression. Without an <b>/L</b> modifier, NULL is passed as the tables
269 pointer; that is, <b>/L</b> applies only to the expression on which it appears.
270 </P>
271 <P>
272 The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
273 compiled pattern (whether it is anchored, has a fixed first character, and
274 so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
275 pattern. If the pattern is studied, the results of that are also output.
276 </P>
277 <P>
278 The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
279 <b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers.
280 </P>
281 <P>
282 The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
283 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
284 facility is for testing the feature in PCRE that allows it to execute patterns
285 that were compiled on a host with a different endianness. This feature is not
286 available when the POSIX interface to PCRE is being used, that is, when the
287 <b>/P</b> pattern modifier is specified. See also the section about saving and
288 reloading compiled patterns below.
289 </P>
290 <P>
291 The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
292 expression has been compiled, and the results used when the expression is
293 matched.
294 </P>
295 <P>
296 The <b>/M</b> modifier causes the size of memory block used to hold the compiled
297 pattern to be output.
298 </P>
299 <P>
300 The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
301 API rather than its native API. When this is done, all other modifiers except
302 <b>/i</b>, <b>/m</b>, and <b>/+</b> are ignored. REG_ICASE is set if <b>/i</b> is
303 present, and REG_NEWLINE is set if <b>/m</b> is present. The wrapper functions
304 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
305 </P>
306 <P>
307 The <b>/8</b> modifier causes <b>pcretest</b> to call PCRE with the PCRE_UTF8
308 option set. This turns on support for UTF-8 character handling in PCRE,
309 provided that it was compiled with this support enabled. This modifier also
310 causes any non-printing characters in output strings to be printed using the
311 \x{hh...} notation if they are valid UTF-8 sequences.
312 </P>
313 <P>
314 If the <b>/?</b> modifier is used with <b>/8</b>, it causes <b>pcretest</b> to
315 call <b>pcre_compile()</b> with the PCRE_NO_UTF8_CHECK option, to suppress the
316 checking of the string for UTF-8 validity.
317 </P>
318 <br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
319 <P>
320 Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
321 whitespace is removed, and it is then scanned for \ escapes. Some of these are
322 pretty esoteric features, intended for checking out some of the more
323 complicated features of PCRE. If you are just testing "ordinary" regular
324 expressions, you probably don't need any of these. The following escapes are
325 recognized:
326 <pre>
327 \a alarm (BEL, \x07)
328 \b backspace (\x08)
329 \e escape (\x27)
330 \f formfeed (\x0c)
331 \n newline (\x0a)
332 \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
333 \r carriage return (\x0d)
334 \t tab (\x09)
335 \v vertical tab (\x0b)
336 \nnn octal character (up to 3 octal digits)
337 \xhh hexadecimal character (up to 2 hex digits)
338 \x{hh...} hexadecimal character, any number of digits in UTF-8 mode
339 \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
340 \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
341 \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
342 \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
343 ated by next non alphanumeric character)
344 \C+ show the current captured substrings at callout time
345 \C- do not supply a callout function
346 \C!n return 1 instead of 0 when callout number n is reached
347 \C!n!m return 1 instead of 0 when callout number n is reached for the nth time
348 \C*n pass the number n (may be negative) as callout data; this is used as the callout return value
349 \D use the <b>pcre_dfa_exec()</b> match function
350 \F only shortest match for <b>pcre_dfa_exec()</b>
351 \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
352 \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
353 ated by next non-alphanumeric character)
354 \L call pcre_get_substringlist() after a successful match
355 \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
356 \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
357 \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
358 \P pass the PCRE_PARTIAL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
359 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
360 \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
361 \S output details of memory get/free calls during matching
362 \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
363 \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
364 \&#62;dd start the match at offset dd (any number of digits);
365 this sets the <i>startoffset</i> argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
366 \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
367 \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
368 \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
369 \&#60;anycrlf&#62; pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
370 \&#60;any&#62; pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
371 </pre>
372 The escapes that specify line ending sequences are literal strings, exactly as
373 shown. No more than one newline setting should be present in any data line.
374 </P>
375 <P>
376 A backslash followed by anything else just escapes the anything else. If
377 the very last character is a backslash, it is ignored. This gives a way of
378 passing an empty line as data, since a real empty line terminates the data
379 input.
380 </P>
381 <P>
382 If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
383 different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
384 fields of the <b>pcre_extra</b> data structure, until it finds the minimum
385 numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
386 <i>match_limit</i> number is a measure of the amount of backtracking that takes
387 place, and checking it out can be instructive. For most simple matches, the
388 number is quite small, but for patterns with very large numbers of matching
389 possibilities, it can become large very quickly with increasing length of
390 subject string. The <i>match_limit_recursion</i> number is a measure of how much
391 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
392 to complete the match attempt.
393 </P>
394 <P>
395 When \O is used, the value specified may be higher or lower than the size set
396 by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
397 the call of <b>pcre_exec()</b> for the line in which it appears.
398 </P>
399 <P>
400 If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
401 API to be used, the only option-setting sequences that have any effect are \B
402 and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
403 <b>regexec()</b>.
404 </P>
405 <P>
406 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
407 of the <b>/8</b> modifier on the pattern. It is recognized always. There may be
408 any number of hexadecimal digits inside the braces. The result is from one to
409 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
410 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
411 valid Unicode code points, or indeed valid UTF-8 characters according to the
412 later rules in RFC 3629.
413 </P>
414 <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
415 <P>
416 By default, <b>pcretest</b> uses the standard PCRE matching function,
417 <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
418 alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
419 different way, and has some restrictions. The differences between the two
420 functions are described in the
421 <a href="pcrematching.html"><b>pcrematching</b></a>
422 documentation.
423 </P>
424 <P>
425 If a data line contains the \D escape sequence, or if the command line
426 contains the <b>-dfa</b> option, the alternative matching function is called.
427 This function finds all possible matches at a given point. If, however, the \F
428 escape sequence is present in the data line, it stops after the first match is
429 found. This is always the shortest possible match.
430 </P>
431 <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
432 <P>
433 This section describes the output when the normal matching function,
434 <b>pcre_exec()</b>, is being used.
435 </P>
436 <P>
437 When a match succeeds, pcretest outputs the list of captured substrings that
438 <b>pcre_exec()</b> returns, starting with number 0 for the string that matched
439 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
440 when <b>pcre_exec()</b> returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
441 respectively, and otherwise the PCRE negative error number. Here is an example
442 of an interactive <b>pcretest</b> run.
443 <pre>
444 $ pcretest
445 PCRE version 7.0 30-Nov-2006
446
447 re&#62; /^abc(\d+)/
448 data&#62; abc123
449 0: abc123
450 1: 123
451 data&#62; xyz
452 No match
453 </pre>
454 If the strings contain any non-printing characters, they are output as \0x
455 escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
456 pattern. See below for the definition of non-printing characters. If the
457 pattern has the <b>/+</b> modifier, the output for substring 0 is followed by
458 the the rest of the subject string, identified by "0+" like this:
459 <pre>
460 re&#62; /cat/+
461 data&#62; cataract
462 0: cat
463 0+ aract
464 </pre>
465 If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
466 matching attempts are output in sequence, like this:
467 <pre>
468 re&#62; /\Bi(\w\w)/g
469 data&#62; Mississippi
470 0: iss
471 1: ss
472 0: iss
473 1: ss
474 0: ipp
475 1: pp
476 </pre>
477 "No match" is output only if the first match attempt fails.
478 </P>
479 <P>
480 If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
481 data line that is successfully matched, the substrings extracted by the
482 convenience functions are output with C, G, or L after the string number
483 instead of a colon. This is in addition to the normal full list. The string
484 length (that is, the return from the extraction function) is given in
485 parentheses after each string for <b>\C</b> and <b>\G</b>.
486 </P>
487 <P>
488 Note that whereas patterns can be continued over several lines (a plain "&#62;"
489 prompt is used for continuations), data lines may not. However newlines can be
490 included in data by means of the \n escape (or \r, \r\n, etc., depending on
491 the newline sequence setting).
492 </P>
493 <br><a name="SEC8" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
494 <P>
495 When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
496 means of the \D escape sequence or the <b>-dfa</b> command line option), the
497 output consists of a list of all the matches that start at the first point in
498 the subject where there is at least one match. For example:
499 <pre>
500 re&#62; /(tang|tangerine|tan)/
501 data&#62; yellow tangerine\D
502 0: tangerine
503 1: tang
504 2: tan
505 </pre>
506 (Using the normal matching function on this data finds only "tang".) The
507 longest matching string is always given first (and numbered zero).
508 </P>
509 <P>
510 If <b>/g</b> is present on the pattern, the search for further matches resumes
511 at the end of the longest match. For example:
512 <pre>
513 re&#62; /(tang|tangerine|tan)/g
514 data&#62; yellow tangerine and tangy sultana\D
515 0: tangerine
516 1: tang
517 2: tan
518 0: tang
519 1: tan
520 0: tan
521 </pre>
522 Since the matching function does not support substring capture, the escape
523 sequences that are concerned with captured substrings are not relevant.
524 </P>
525 <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
526 <P>
527 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
528 indicating that the subject partially matched the pattern, you can restart the
529 match with additional subject data by means of the \R escape sequence. For
530 example:
531 <pre>
532 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
533 data&#62; 23ja\P\D
534 Partial match: 23ja
535 data&#62; n05\R\D
536 0: n05
537 </pre>
538 For further information about partial matching, see the
539 <a href="pcrepartial.html"><b>pcrepartial</b></a>
540 documentation.
541 </P>
542 <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
543 <P>
544 If the pattern contains any callout requests, <b>pcretest</b>'s callout function
545 is called during matching. This works with both matching functions. By default,
546 the called function displays the callout number, the start and current
547 positions in the text at the callout time, and the next pattern item to be
548 tested. For example, the output
549 <pre>
550 ---&#62;pqrabcdef
551 0 ^ ^ \d
552 </pre>
553 indicates that callout number 0 occurred for a match attempt starting at the
554 fourth character of the subject string, when the pointer was at the seventh
555 character of the data, and when the next pattern item was \d. Just one
556 circumflex is output if the start and current positions are the same.
557 </P>
558 <P>
559 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
560 result of the <b>/C</b> pattern modifier. In this case, instead of showing the
561 callout number, the offset in the pattern, preceded by a plus, is output. For
562 example:
563 <pre>
564 re&#62; /\d?[A-E]\*/C
565 data&#62; E*
566 ---&#62;E*
567 +0 ^ \d?
568 +3 ^ [A-E]
569 +8 ^^ \*
570 +10 ^ ^
571 0: E*
572 </pre>
573 The callout function in <b>pcretest</b> returns zero (carry on matching) by
574 default, but you can use a \C item in a data line (as described above) to
575 change this.
576 </P>
577 <P>
578 Inserting callouts can be helpful when using <b>pcretest</b> to check
579 complicated regular expressions. For further information about callouts, see
580 the
581 <a href="pcrecallout.html"><b>pcrecallout</b></a>
582 documentation.
583 </P>
584 <br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
585 <P>
586 When <b>pcretest</b> is outputting text in the compiled version of a pattern,
587 bytes other than 32-126 are always treated as non-printing characters are are
588 therefore shown as hex escapes.
589 </P>
590 <P>
591 When <b>pcretest</b> is outputting text that is a matched part of a subject
592 string, it behaves in the same way, unless a different locale has been set for
593 the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b>
594 function to distinguish printing and non-printing characters.
595 </P>
596 <br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
597 <P>
598 The facilities described in this section are not available when the POSIX
599 inteface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
600 specified.
601 </P>
602 <P>
603 When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
604 compiled pattern to a file, by following the modifiers with &#62; and a file name.
605 For example:
606 <pre>
607 /pattern/im &#62;/some/file
608 </pre>
609 See the
610 <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
611 documentation for a discussion about saving and re-using compiled patterns.
612 </P>
613 <P>
614 The data that is written is binary. The first eight bytes are the length of the
615 compiled pattern data followed by the length of the optional study data, each
616 written as four bytes in big-endian order (most significant byte first). If
617 there is no study data (either the pattern was not studied, or studying did not
618 return any data), the second length is zero. The lengths are followed by an
619 exact copy of the compiled pattern. If there is additional study data, this
620 follows immediately after the compiled pattern. After writing the file,
621 <b>pcretest</b> expects to read a new pattern.
622 </P>
623 <P>
624 A saved pattern can be reloaded into <b>pcretest</b> by specifing &#60; and a file
625 name instead of a pattern. The name of the file must not contain a &#60; character,
626 as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by &#60;
627 characters.
628 For example:
629 <pre>
630 re&#62; &#60;/some/file
631 Compiled regex loaded from /some/file
632 No study data
633 </pre>
634 When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
635 the usual way.
636 </P>
637 <P>
638 You can copy a file written by <b>pcretest</b> to a different host and reload it
639 there, even if the new host has opposite endianness to the one on which the
640 pattern was compiled. For example, you can compile on an i86 machine and run on
641 a SPARC machine.
642 </P>
643 <P>
644 File names for saving and reloading can be absolute or relative, but note that
645 the shell facility of expanding a file name that starts with a tilde (~) is not
646 available.
647 </P>
648 <P>
649 The ability to save and reload files in <b>pcretest</b> is intended for testing
650 and experimentation. It is not intended for production use because only a
651 single pattern can be written to a file. Furthermore, there is no facility for
652 supplying custom character tables for use with a reloaded pattern. If the
653 original pattern was compiled with custom tables, an attempt to match a subject
654 string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
655 Finally, if you attempt to load a file that is not in the correct format, the
656 result is undefined.
657 </P>
658 <br><a name="SEC13" href="#TOC1">SEE ALSO</a><br>
659 <P>
660 <b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
661 <b>pcrepartial</b>(d), <b>pcrepattern</b>(3), <b>pcreprecompile</b>(3).
662 </P>
663 <br><a name="SEC14" href="#TOC1">AUTHOR</a><br>
664 <P>
665 Philip Hazel
666 <br>
667 University Computing Service
668 <br>
669 Cambridge CB2 3QH, England.
670 <br>
671 </P>
672 <br><a name="SEC15" href="#TOC1">REVISION</a><br>
673 <P>
674 Last updated: 09 August 2007
675 <br>
676 Copyright &copy; 1997-2007 University of Cambridge.
677 <br>
678 <p>
679 Return to the <a href="index.html">PCRE index page</a>.
680 </p>

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